1. Field of the Invention
The present invention relates generally to actuators configured to drive or to actuate a device using electrowetting, and pumps and optical scanners comprising such an actuator.
2. Description of Related Art
Electrowetting is a known phenomenon in which when a potential difference is applied between an electrode covered by an insulating layer and a liquid droplet positioned on a surface of the insulating layer, a wetting or contact angle of the droplet with respect to the surface of the insulating layer is altered due to changes in interfacial tension between the droplet and the surface of the insulating layer. Recently, principles associated with these changes in liquid droplet behavior based on electrowetting have been applied to actuators. Specifically, the driving power of actuators employing electrowetting more readily may be saved than the driving power of actuators employing motors and piezoelectric actuators. Moreover, actuators employing electrowetting may have a less complex structure than actuators employing motors and piezoelectric actuators, which may decrease the size of the actuator.
A known device employing electrowetting, such as the device described in Japanese Laid-open Patent Publication No. 2005-185090, applies electrowetting to a drive device (actuator) which is driven when a focus of a camera lens is adjusted. The known device includes a first body and a second body which opposes the first body, such that the second body selectively mores closer to and further away from the first body, and a liquid droplet positioned between the first body and the second body, such that the liquid droplet contacts the first body and the second body. The wetting angle of the liquid with respect to a surface of the body which the droplet contacts is altered by electrowetting. Thus, the height of the droplet between the first body and the second body is altered to adjust the distance between the first body and the second structure body.
The drive device drives the first body and the second body, such that they selectively move closer to and further away from each other. Nevertheless, such a drive device may not always be suitable for subtle adjustments of drive amounts.